During a study of Caribbean sponges, several sponges of the genus Agelas were examined and all gave ethanolic extracts having antimicrobial activity, in agreement with previous reports. Burkholder, P. R. in "Biology and Geology of Coral Reefs, Biology I"; Jones, O. A.; Endean, R., Eds.; Academic Press: New York, 1973; p. 144. Prior studies by Minale et al., Minale, L.; Cimino, G.; de Stefano, S.; Sodano, G. Prog. Chem. Nat. Prod. 1976, 33, 1 resulted in the identification of 4,5-dibromo-2-cyanopyrrole as the antimicrobial constituent of the Mediterranean sponge Angelas oroides. A. oroides also contained 4,5-dibromopyrrole-2-carboxylic acid, Forenza, S. L.; Minale, L.; Riccio, R.; Fattorusso, E. Chem. Commum. 1971, 1129, the corresponding amide, and oroidin having the formula: ##STR2##
According to this invention, we have now discovered the major antimicrobial constituent of Agelas sceptrum (Lamarck), Agelas conifera, Agelas schmidti, an unknown sponge species from Canton atoll in the South Pacific (collection No. 78-012) and an unknown sponge, Axinella sp., from Belize which have been found to possess superior antimicrobial properties.